History of British animals - University of Guam Marine Laboratory

MO MOLLUSCA. PSAMMOBIADJ5. Astaetjs.it is known in the north of Scotland by the trivial name of " Brown circularfurrowed northern Cockle"—a descriptive epithet we have not heard of, andwhich seems somewhat different from the usual provincial appellations.501. A. Danmonice.— Shell transversely ovate, with strong,regular, equidistant, concentric smooth ridges.Venus Dan. Mont. Test. Brit. Sup. 45. t. xxix. f. 4 Crassina sulcata,Turt. Biv. Brit. 131. t. xi. f. 1, 2— English and Scottish coasts.Length an inch, breadth an inch and a quarter ; shell white, with a darkbrowncuticle ; beaks nearly central, inclining, below which is a lanceolatedepression ; margin within glossy and crenulated ; teeth, two in each valve.*Margin plain.— 502. A. Scotica. — Shell transversely ovate, with strong,regular,equidistant, concentric, smooth ridges.Venus Scotica, Maton and Ilackelt, Linn. Trans, viii. pt. 1. t. ii. f. 3.Mont. Test. Brit. Supp. 44—Crassina Scotica, Turt. Biv. Brit. 130.t. xi. f. 3, 4—Various parts of the coast, from Devon to Zetland.Length T 7 5 ths, breadth an inch ; white with a brown cuticle. It is principallydistinguished from the preceding by the greater compression of theventral margin, the shortness of the lunule, and in the inside being lessrough, and the margin entire.503. A. compressa.— Shell subtriangular, rounded in front ;beaks very prominent, and inclining;obsoletely and irregularlysulcatcd transversely.Venus compressa, Mont. Test. Brit. Sup. 43. t. xxvi. f. 1—Maton andRackctt, Linn. Trans, viii. t. ii. f. 2— Cyprina compressa, Turt. Biv.Brit. 13C. t. xi. f. 20-23—Coast of Scotland.Diameter about half an inch shell ; white, with a brown cuticle ;cartilageslope but little rounded ;the depression in front of the beaks sudden. Whilethe figure in the Linn. Trans, above quoted belongs to this species, the descriptionis that of A. sulcata. I possess dead valves from St Andrew's Bayupwards of an inch and three-tenths in length. Is this distinct from Crassinasemisulcata of Dr Leach, Annals of Philosophy, xiv. 204. ? Even by theaid of authentic specimens, I have failed to procure a specific difference.EXTINCT SPECIES.I. A. lurida— Transversely oblong, convex, depressed, with many transverseundulations ;lunette elliptical, sharp ; margin crenulated within, nearlystraight ventrally.— Sower. Min. Conch, t. exxxvii. f. 1 Inferior Oolite.2. A. clegan-s — Transversely oblong, convex, depressed, with many smallcrenulated within.—Sower. Min.transverse costa?, lunette cordate ;marginConch, t. exxxvii. f. 3— Inferior Oolite.3. A. cuneaia— Subcordate, acuminated, gibbose, with small transversecostae; lunette cordate; margin entire within.—Sower. Min. Conch, t.cxxxvii.f. 2.— Upper Oolite.4. A. plana— Nearly orbicular, depressed, surface plain ;lunette elongated,acute, deep; margin entire.—Sower. Min. Conch. 179. £ 2.— Crag?5. A. obliquata Obovate, transversely depressed with ; many oblique concentricstriaeupon the surface ; margin crenulated.—Sower. Min. Concht,clxxix. f. 3 In Crag.